• Botrytis cinerea
• grapevine berry
• nutritional supplement
• Real Time RT-PCR
• ripening
• stilbenoids
• wounding

Gray mold caused by Botrytis cinerea is a serious disease in most wine producing countries. The symptoms of the disease (bunch rot) can result from the expression of latent B. cinerea or from external infections of the grapevine berry, whose susceptibility increases during ripening. In this work, the interaction between B. cinerea and berries of the cultivated grapevine (Vitis vinifera L.) was studied at molecular level by integrating metabolic and gene expression data. Since it is known that developmental stage of the berry, presence of skin ruptures and the availability of nutrients for the fungus, are key parameters in determining disease progression, detached berries of the cv. Pinot noir either at véraison or ripe stage were artificially inoculated with B. cinerea upon wounding or in the presence of nutritional supplement. Disease progression evaluation from 24 hours post inoculation (hpi) till 8 days post inoculation (dpi) demonstrated that the disease is strongly dependent on the stage of berry development and on the inoculation conditions. In particular, ripe stage and presence of injury significantly favor Botrytis growth. To further investigate the molecular mechanisms behind this response, berry skin samples collected at 6, 12, 24 hpi were analyzed for polyphenol content and expression of selected genes of the host and of the pathogen. Véraison berries responded by activating genes encoding for a polygalacturonase-inhibiting protein or involved in stilbenoids biosynthesis as well as by accumulating different type of stilbenoids. Some of the genes and stilbenoids were induced both in response to B. cinerea and to wounding, while others were specific to one of the two responses. On the other hand, the response of ripe berries was apparently too slow to halt fungal infection, as it appears from the time course considered in the present study. The fungal genes involved in pectin degradation and in phytotoxins production, as well as in the oligomerization of trans-resveratrol, were significantly induced or repressed by injury and by nutritional supplement independently of the berry stage. This study suggests that the limited susceptibility of the berry at véraison stage is likely due to a larger extent to a prompt defense response of the plant tissue rather than to a reduced virulence of the pathogen.